After reaching metaphase II, in vitro matured oocytes undergo the complex processes referred to as oocyte aging. Under the culture conditions, some aged oocytes remained at the stage of metaphase II, some underwent spontaneous parthenogenetic activationand others underwent cellular death, either through apoptosis (fragmentation) or lysis. We investigated the effect of c-Jun N-terminal kinases (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) inhibition on pig oocyte aging and the activity of JNK and p38 MAPK during the aging period. Based on our data, we can conclude that JNK plays active role in fragmentation of pig oocytes and that p38 MAPK is not involved in this process.